Soap product and method of making same



Patentedlluly 8, 1947 UNITED STATES SOAP PRODUCT AND METHOD OF MAKING SAME Stanley Joseph Holuba, North Bergen, N. J., as-

. slgnor to Colgate-Palmolive-Peet Company,

Jersey City, N. J a corporation of Delaware No Drawing. Application September as, 1943,

Serial No. 504,162

16 Claims. 1

The present invention relates to a process of treating soap particles to reduce dust and lumping tendencies therein and, more particularly, of coating fatty acid soaps in sprayed, granulated and chip form, and to the product of such process.

Spray-dried soaps, granulated soaps and chip soaps have been employed for many years, both in industrial and domestic use. Because of their large exposed surface area, they possess the obvious advantage of being relatively easy to dissolve in water. There is always, however, an

appreciable portion of fines, which causes a dust nuisance. This'dust nuisance is caused by that portion of the particles which is extremely fine, so that, upon being disturbed, they form a cloud in the immediate vicinity. An indication of the relative proportions of dust in various soaps is sometimes provided by screen analyses, and the material passing through a 100- or 200-mesh screen comprises what may be termed "dust particles. Their nuisance character increases as the dust particles become smaller' in size. Some dust may be incidental to the process of manufacturing soap particles, but the more undesirable, extremely fine particles apparently result from mechanical action of the larger particles against each other during handling, packaging and transportation, the most troublesome or irritating dust usually being produced by disintegration of the coarser particles. The resulting powder may be very small in percentage but very objectionable because of fineness and number of particles.

Spray-dried soaps and granulated soaps usually show considerably lumping tendencies also, that is, the tendency of the soap to agglomerate when poured onto water. This tendency appears to be of increased magnitude in the presence of soluble salts, such as soda ash and the salts of the phosphoric acids, which are frequently employed as soap builders and water softeners. The proportion of fines comprised in particles of soap also appear to influence the lumping tendencies, as a small amount of water, particularly warm water, causes a heavy gel to form between the particles. The particles are thus not so free to dissolve as in their original form. The lumps that form are difllcultto dissolve, even upon vigorous agitation, and they are undesirable because they have a tendency to stick to articles put into the water and because they considerably reduce the efficiency of the soap. When no real attempt is made to put these lumps into solution, as in domestic use, the disadvantages are increased.

In seeking a method for eliminating these disadvantages, the prior art has been directed to removing the fines before packaging the product. Although a reduction in the quantity of fines results in a reduced lumping tendency, there is relatively little effect on the dust-forming tendency. Moreover, the operation is expensive and has the further disadvantage of removing those particles which are individually most easily soluble.

It is an object of the present. invention to provide an improved process for treating fatty acid soaps, during the manufacture of said soaps, in sprayed, granulated and chip forms, to reduce dust.

It is also an object of this invention to provide a process for treating soap beads and granules to reduce lumping tendencies therein.

Another object of the invention is to provide a process for controlling the apparent density of soap particles.

The invention further provides soaps in particulate form having reduced tendencies to dust or to lump.

Other objects and advantages of the invention will be apparent from the following description.

Briefly, the process of the invention comprises applying a water-soluble, siliceous material to the surfaces of soap particles. This process pro ,vides a product which has considerably less tendency to form dust or to lump than the non-tacky or dry condition.

The improved soap particles of this invention exhibit only slight dust-forming tendencies, as

compared with untreated particles. Upon pouring the treated particles into water, they spread over the surface much more readily than do soaps of the same type which have not been so treated, thus facilitating the wetting and dissolution of the soap in the water and avoiding or reducing the formation of aggregates or agglomerates of wet soap particles.

Arbitrary tests for comparing the tendency of various materials to form dust or to lump have been set up, and it is believed that these tests provide good indices of these characteristics in the materials tested. In the lumping test, 15 grams of the material to be tested are poured upon the surface of a liter of water in a beaker at C. The material is allowed to stand one minute and is then vigorously stirred for ten seconds. The resulting mixture is poured through a 10x10 screen, the foam is blown away. and the material retained upon the screen is weighed in its wet form. The weight is taken as a measure of the lumping tendency of the particular material.

The dust test is a visual test. The material to be tested is poured into a large funnel, the tip of the stem of which is 12 inches above the bottom of a receiving vessel. The soap is suddenly dropped through the funnel into this vessel, and the cloud of dust which arises is observed and estimated.

In treating soap particles in the manufacture of the improved sprayed soap of the invention, various methods of applying the siliceous material may be employed, such as spraying soap particles with a silicate solution during their passage through a rotating drum; spraying the soap particles with silicate solution at the bottom of th tower in which the soap particles are i made by spray-drying, or spraying them in a second (or "post-drying) tower; spraying the silicate solution upon a cascade of soap particles before and/or after cooling; tumbling the particles, particularly after cooling, through a fine stream of silicate solution, etc. According to a preferred method, the soap particles are formed by spraying a soap slurry into a tower, as is well known in the art, and the resulting soap grains or beads are passed to a rotating cooling drum wherein they are tumbied'while the silicate solution is prayed upon them. This method of coating the soap particles (1, e., applying siliceous material to their surfaces) by spraying may also be employed in reducing the dust otherwise occurring in soap products resulting from the granulation of a mechanical mixture of soap chips and dry builders. Sodium silicate is frequently used as a constituent of various soap products, whether incorporated in each particle or present in a mechanical mixture, and the amount of silicate used as a coating may b in addition to, or

in lieu of part or all of, the silicate normally employed.

The proportion of silicate to be applied to, the I soap particles may vary widely. In general, a proportion of sodium silicate of about 2% or higher, up to the amount of silicat usually present as a builder, is preferred, but the invention is not limited to these proportions. Thus, proportions considerably below 2% of sodium silicate are effective in reducing dust and in decreasing lumping tendencies. Similarly, while proportions of sodium silicate above about 6% (on the dry basis) in the finished product are seldom employed, so that high detergency may be maintained, it will be understood from the foregoing that considerably higher proportions of silicate may be used, if desired.

The temperature at which the silicate solution is applied to the soap particles may vary over a considerable range. Thus, a colder silicate solution, e. g., a solution at about room temperature, sets faster and forms va coating uponthe particles more quickly than when a hot solution is used. The application of a' cool solutionis F. to about F. provide satisfactory results when preparing a product to have an apparent density of about 0.4 gram per cubic centimeter. Spray-dried soap particles may be treated in accordance with the invention in .a cooling drum within the drum at which the spraying takes place are factors in determining the apparent density of the product. When using a long cooling drum in continuous operation, so that the soap particles are at'about room temperature (e. g., about 65 F. to about 90v F.) when discharged therefrom, 'a product of apparent density lighter than that of the original particles can be obtained by spraying the silicate solu-- tion thereupon at or near the discharge end of the drum Whenv a spray-dried soap of heavier density is desired, the soap beads are preferably sprayed at the inlet end ofvthe cooling drum. Soap particles delivered directly to the cooling drum from a spray tower are commonly at a temperature of about F.

When the silicate solution is sprayed at or near the inlet of the drum, the product may exhibit lumping in use. An'efl'ective method of providing soap beads of relatively heavy density (that is, about 0.5 gram per cubic centimeter) and which yet retain the non-lumping charadaerlstics of the lighter coated product is to spray the soap beads with silicate solution at or near the inlet end of the cooling drum and then to respray the particles at or near the discharge end.

of the drum.

The step of spraying silicate solution upon the soap particles adds moisture to them, so that it is desirable to take this fact into consideration when preparing the beads for silicate spraying.

This is conveniently done by modifying the operation of the spray tower in order to'reduce the amount of moisture present in the soap beads from the amount normally present when passing to the cooling drum.

also of assistance in reducing the temperature of hot soap particles. In spite of these factors which favor the use of cool silicate solutions, it

is sometimes advisable to use a hot solution.

Thus, with other factors the same, the higher the temperature of the silicate solution, the greater is the apparent density of the coated product. By "apparent density". of the product of the process is meant the weight of an amount of the material which occupies a unit volume, including thevvolume of interstitial spaces, pores and cavities. In general, temperatures of about A sample of untreated sprayed soap beads produced in a tower was found .to give a sieve analy- This material gave a considerable dust cloud when dropped through the 12-inch distance, described in connection with the dust test supra. The material also showed lumping of about 14.0 grams.

The foregoing is a typical example of the materlal produced in a spray tower. There is, however, considerable variation in sieve'analyses among materials of this type, the proportion on the 40-mesh sieve usually being of the order of about 20% to about 30% of the material and the proportion on the 60-mesh sieve running about 25% to about 40%. Lumpin-g is of the order of about 10.0 to about 18.0 grams in this material, as measured by the lumping test described supra. The apparent density of the material varies from. about 0.40 to about 0.43 gram per cubic centimeter. 7

The following examples are merely illustrative of the present invention, and it will be understood that the invention is not limited thereto.

Example I The following ingredients are put into a crutcher and mixed:

This mixture is then passed to a spray tower and is sprayed into a stream of air. All but about 12% moisture is removed in the spray tower, and

a product having an apparent density of 0.42 gram per cubic centimeter is obtained. After standing for some days, the beads dry to a moisture content of approximately 7%. Ten parts by weight of a solution of sodium silicate, comprising 8 parts of commercial 38.4% sodium silicate solution (1 part NazO:3.26 parts S102) and 2 parts of water, is sprayed at 110 F. upon '72 parts of soap beads in a rotating drum, the beads and drum, before spraying with silicate, being at about; 75 F. The beads are vigorously tumbled during the spraying. After an additional two minutes of tumbling, the product is dried to about 14% moisture.

The product has an apparent density of 0.37 gram per cubic centimeter, gives no visually perceptible' dust cloud upon being subjected to the dust test described above, shows lumping of only 1.5 grams, possesses good detergent properties,

and gives the following sieve analysis:

TABLE II Sieve Per cent n lz-mesh About 0.1 On 20-me h About 15. 9 On 40-mesh About 50. 1 On 60-mesh About 23.1 On 80-mesh. About 5. 6 0n 100-mesh. About 1. 8 Thru 100-mesh About 3. 4

Ewample II About 97 parts by weight of the untreated soap beads of 7% moisture content made in Example I are placed in a rotating drum at 75 F. and are there sprayed with 10 parts of a 30% aqueous solution of sodium orthosilicate (1 part NazO:0.5 part SiOz) at a temperature of 120 F. The beads are vigorously tumbled in the drum during the spraying and for about five minutes thereafter. The product is spread out to dry for a half hour and is then examined. There is no visually perceptible dust, and the lumping test gives a value of only 2.5 grams.

Example 11! A soap composition is made up as follows:

The materials are mixed together and are sprayed into a stream of air in a spray tower. The tower is operated to remove all but about 8% of the moisture content, and the resulting soap beads have an apparent density of 0.41 gram per cubic centimeter. The beads are passed to a cooling drum, which has a length of forty feet and is provided with baflle plates and adapted to be rotated. In the fifteen feet nearest the discharge end of the drum, three fine sprays (#51 drill) are provided, and these are spaced from each other approximately equidistantly along the fifteen feet. A 28% aqeous solution of sodium silicate (1 part Naz023.26 parts SiOz) under a gauge pressure of 100 pounds per square inch and at F.is introduced into the drum through the three sprays, and, while the soap particles are being tumbled in the drum, the solution is sprayed upon the particles at a rate suflicient to add about 3% of sodium silicate on the dry basis. The material is discharged from the drum at a moisture content of about 12% and has an apparent density of 0.38 grams, and there is practically no dust. The sieve analysis of the product is as follows TABLE III Sieve Per cent On l2-mesh On 20-mesh Example IV Employing soap beads produced in the spray tower as described in Example III, the beads pass into the inlet end of the drum at a rate of about parts by weight per minute and at a temperature of 135 F. The beads are sprayed at the inlet end with about 10 parts by weight per minute of a 12% aqueous solution of sodium silicate (1 part NazO:2.35 parts SiOa) at F. The beads are tumbled through the length of the drum and are resprayed at the discharge end thereof with about 10 parts per minute of a 24% aqueous solution of sodium silicate (1 part NazO:3.26 parts SiO2) at 75 F. The product has an apparent density of about 0.53 gram per cubic centimeter, shows no visually perceptible dust when subjected to the dust test, and exhibits lumping of 4.7 grams.

Granular soap powders are also improved treatment in accordance with this invention.

.Soap powders, particularly those containing relaseacu besides reducing dust, provides particles having little tendency to cake, as the hygroscopic materials present in th soap powder are inhibited from growing. The process may also be employed to control the apparent density of the product.

Example V A soap powder formula is made up by crutching The mixture is sprayed into a stream of cold air in a spray tower, and the particles falling therethrough are sprayed near the bottom of the tower with a 28.8% aqueous solution of sodium silicate (1 part NazO:3.26 parts S102) in sufllcient amount to add about 4% sodium silicate on the dry basis. The material is then screened, and a non-caking, substantially dust-free soap powder is provided.

A desirable product may be obtained by modityin the silicate coating with various adjuvant materials. Thus, reduced lumping is exhibited by applying to soap grains or beads, in addition to sodium silicate solution, an amount of a binding or plasticizing agent which is either soluble in water (e. g., various gums and waxes, including Carbowax, a water-soluble polymerized ethyl- 'ene oxide) or ,sufllciently low-melting so as to melt in warm water (e. g., certain solid paraflins, especially when mixed with a liquid mineral oil).

Example VI Spray-dried soap beads are produced by crutching the same proportion of ingredients as in Example I, the mixture being sprayed into a stream of air in a spray tower and the tower being operated to produce a, product of approximately 12% moisture. After some days, when the beads have dried to a moisture content of about 7 93 parts by weight of said soap beads having an apparent density of 0.41 gram per cubic centimeter are transferred to a drum, the drum and beads being at about 80 F. A coating composition is made up in the following manner: 1 part of paraffin wax having a melting-point of about 95 F. is

' heated slightly above its melting-point and is mixed with 1 part of heavy white mineral oil; 3 parts of water and 5 parts of a commercial 38.4% aqueous sodium silicate solution (1 part NazO: 3.26- parts SiOa) are added to the mixture. This coat:-

ing composition is kept under agitation, and 10 parts of the mixture is sprayed upon the 93 parts of soap beads in the drum, the beadsbeing vigorously tumbled during the spraying. The tumbling is continued for about two minutes after the beads have been sprayed in order to provide time for the coating to set, and the product is spread outand dried to about 12% moisture. The ap-. parent density of the sprayed soap beads is 0.37 gram per cubic centimeter. Thebeads are aged v for about a week and are then subjected to the lump test described supra; lumping of 0.5 gram is obtained. The product exhibits high detersive efllciency.

, Example VII Soap beads of the same composition as those coated in Examples I and VI are employed, and 93 parts of said beads having a moisture content of about 7 and an apparent density of 0.41 gram per cubic centimeter are transferred to a small drum at a temperature of 80 F. A coating composition is prepared by mixing 6.5 parts by weight of a 28% aqueous sodium silicate solution (1 part Na:0:3.26 parts SiOz) with 8 parts of a 25% aqueou solution of a water-soluble wax sold under the trade name of Carbowax 4000, a polymerized ethylene oxide. The soap beads in the drum are vigorously tumbled and are sprayed with 14.5 parts of the coating com o ition at 80 F. After two minutes additional tumbling, the prodnot is spread out to set and to dry to a moisture content of about 13%. The coated soap beads have a density of 0.38 gram per cubic'centimeter and give lumping of 0.8 gram.

The silicate coating may also be modified-by the addition of pigments and/or organic dyes. Thus, a small proportion of titanium dioxide (e. g., about 0.5% on the dry basis) may be incorporated in the silicate coating to giv a considerably whiter product.

The present invention has been described with reference to illustrative examples and proportions, but it will be appreciated by those skilled in the art that variations and modifications of the invention can be employed and equivalents substituted therefor, without departing from the principles of the invention. Thus, it will be understood that the invention is not limited to the etc., or by neutralization of the various fatty and resin acids in these and other materials. Similarly, the novel soaps and soap compositions may contain any of the soap builders and fillers usually employed by the art or may comprise mineral oils or other emulsifiers. Moreover, while the illustrative examples disclose the-use of sodium silicate solutions for application to the surfaces of the soap particles, a solution of any water-soluble silicate may be employed in this invention. Although water is preferably. employed asthe liquid vehicle for applying the silicate, other easily volatilizable solvents, such as the lower monohydric alcohols, hydrocarbons, cyclic hydrocarbons, aromatic hydrocarbons,'chlorinated hydrocarbons, etc., including methyl and ethyl alcohols, hexane, octane, cyclohexane, benzene, carbon tetrachloride and the like, may be used, and the siliceous material may be dissolved or suspended therein or may be present. in the colloidal state or emulsified therewith. The term particle" used in the present specification and in the appended claims is. intended to include sizes and shapesof material having at least one dimension of relatively low order,

0 such as grains, beads, chips, flakes and other forms having proportionately large surface area.

- Particles havingsolid centers are usually referred 9 from chips and flakes in that all of their dimensions are of relatively low order.

The words coat or coating are not to be understood as limiting. Whether the soap particle is completely enclosed in a film of the siliceous material when sprayed is not known. What is known is that, by applying the silicate solution to the soap particles, as is disclosed and described herein, the objects and advantages desired are attained.

The term drying" as used herein denotes the removal of moisture in excess of that desired in the final product.

I claim:

1. The process which comprises coating preformed soap particles with a water-soluble silicate salt in an amount effective in reducing dust.

2. The process which comprises applying to pre-formed soap particles an amount of a watersoluble silicate salt suificient to coat said particles and to reduce dust-forming tendencies.

3. The process which comprises applying to pre-formed soap particles having all of their dimensions of relatively low order a solution of a water-soluble silicate salt in an amount effective in reducing dust and lumping tendencies, and at least partially drying said particles.

4. The process which comprises applying to .pre-formed soap particles a solution of a watersoluble silicate salt, and at least partially drying said particles to provide a silicate coating thereon, said coating containing silicate salt inv amount at least 2% of the weight of the coated particles on the dry basis.

5. The process which comprises applying to pre-formed soap particles having all of their dimensions of relatively low order a solution of a water-soluble silicate salt, and drying said particles to provide a silicate coating thereon, said coating containing silicate salt in amount about 2% to about 6% of the weightof the coated particles on the dry basis.

6. The process which comprises spraying preformed soap particles with a solution of a watersoluble silicate salt in an amount effective to reduce dust-forming tendencies, and at least partially drying the sprayed particles.

'7. The process which comprises spraying preformed soap particles with a solution of a watersoluble silicate salt, and drying the sprayed particles, said solution being applied in sufficient amount and concentration to provide a coating of the silicate salt upon the surfaces of said particles.

8. The process which comprises spraying preformed soap particles having all of their dimensions of relatively low order, at about 65 F. to about 90 F. with a solution of a water-soluble silicate salt, and drying the sprayed particles.

9. The process which comprises spraying preformed soap particles having all of their dimension of relatively low order at an elevated temp ure up to about 135 F. with a solution of a water-soluble silicate salt, and tumbling, cooling and drying said sprayed particles.

10. The process which comprises spraying preformed soap particles having all oftheir dimensions of relatively low order and at about 65 F. to about 90 F. with a sodium silicate solution, and drying said particles to provide a sodium silicate coating thereon, said coating containing sodium silicate in amount at least 2% of the weight of the coated particles on the dry basis.

11. The process which comprises spraying soap particles having all of their dimensions of relasoluble silicate salt; tumbling, cooling and removing moisture from said sprayed particles; again spraying said cooled and tumbled particles with a solution of a water-soluble silicate salt; and drying said particles to provide a silicate coating thereon, said silicate salt solutions being of sufficient concentration to provide a coating containing silicate salt in amount at least 2% of the weight of the coated particles on the dry basis.

13. The process of increasing the apparentdensity of spray dried soap particles which comprises subjecting the particles to impact while in a sufficiently plastic condition that no substantial increase in fines occurs, and controlling the apparent density by' the amount of impact while maintaining the particles in the same general shape.

14. The process of increasing the apparent density of spray dried soap particles which comprises tumbling the particles while sufiiciently plastic with the aid of heat and moisture that no substantial increase in' fines occurs, and controlling the apparent density of the particles by the amount of tumbling.

15. The process which comprises tumbling spray dried soap particles, increasing the moisture content of said particles during tumbling to such an extent as to render said particles plastic, and controlling the apparent density of the particles by the amount of tumbling after increasing the moisture content.

16. The process which comprises tumbling spray dried soap particles, increasing the moisture content of said particles during tumbling by spraying the particles with an aqueous solution of a silicate salt, and controlling the apparent density of the particles by the temperature of said solution and by the amount of tumbling after spraying. STANLEY JOSEPH HOLUBA.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

